You cannot sell anywhere anymore in India on any online portal if you do not have a GST number, so just forget about it and do something else.
Frankly speaking, I assume that you must be over 60 years and I am also assuming that you do not any previous selling experience and hence I advice you not to waste your time now at this age, this job is very time consuming and comes with lots of headache which you will not be able to cope up with at this time in your life.
